Tsutomu Ichihara

A high performance amorphous Si/sub 1-x/C/sub x/:H thermistor bolometer based on micro-machined structure

A high performance micro-bridge structured thermistor bolometer of D*=8.0/spl times/10/sup 8/ cm Hz/sup 1/2//W has been realized without using vacuum packaging. The temperature change in the bolometer was simulated by a newly developed method based on laminar film theory. The calculated values were found to be in excellent agreement with the experimental data. By optimizing deposition parameters of hydrogenated amorphous silicon carbide (a-Si/sub 1-x/C/sub x/:PI) thin film, we have successfully fabricated superior thermistors with a high temperature coefficient of resistance a and low electronic excess noise. The noise dramatically decreases as the amount of Si-CH/sub 3/ and C-H/sub n/ bonds in a-Si/sub 1-x/C/sub x/:H thin films decreases and as the doping level increases.

Correlation between nanostructure and electron emission characteristics of a ballistic electron surface-emitting device

The operation of ballistic electron emitters based on nanocrystallised poly-silicon (NPS) films has been analyzed by transmission electron microscope (TEM) and energy-dispersive X-ray microanalyzer (EDX). The results of nanostructural analyses indicate that the existence of interconnected nanocrystalline silicon (nc-Si) is a key factor for the efficient ballistic electron emission.

Key role of nanocrystalline feature in porous polycrystalline silicon diodes for efficient ballistic electron emission

The cold electron emission characteristics of nanocrystalline porous polysilicon (PPS) diodes have been investigated for two PPS diodes prepared under different conditions. The origin of the difference in the emission efficiency and electron energy distribution between the two samples is analyzed in relation to the respective photoluminescence properties. The photoluminescence spectrum in the efficient electron emitter consists of red and blue emission bands corresponding to nanocrystalline silicon and interfacial oxide, respectively, while that in the low-efficiency emitter consists only of a blue band. Too much oxidation results in a reduction of the emission efficiency due to increased electron scattering. It is evident that both the formation of nanocrystalline silicon and its appropriate surface oxidation are key issues for obtaining efficient ballistic emission. These results are consistent with the emission model that electrons are accelerated in the PPS layer by multiple tunneling through interfac...

Annealing effects on the operation stability of ballistic electron emission from electrochemically oxidized nanocrystalline silicon diodes

To improve the operation life of ballistic electron emission from nanocrystalline silicon diodes, thermal annealing effects have been studied for polycrystalline silicon (poly-Si) based devices. The experimental devices are constructed by sequentially depositing tungsten, anodized nanocrystalline poly-Si (NPS), and gold films upon glass substrates. The NPS films are partially oxidized by electrochemical oxidation treatment, and then annealed at 550 °C in vacuum or in a forming gas ambient. The electron emission efficiency and stability are investigated in relation to the compositional characterization of the respective NPS layers by thermal desorption spectroscopy. It is shown that removal of incorporated H2O molecules and hydrogen-related species from interfacial SiO2 films between silicon nanocrystallites is very effective to suppress interfacial scattering losses of electrons and to enhance the ballistic emission stability for long-term operation.

Fabrication of a 7.6-in.-diagonal prototype ballistic electron surface-emitting display on a glass substrate

A prototype ballistic electron surface-emitting display (BSD) was fabricated on a TFT or PDP glass substrate by using a low-temperature process. A 84 x 63-pixel, 7.6-in.-diagonal full-color BSD shows excellent performance, comparable to the previously reported 2.6-in. model. This result demonstrates the strong possibility of large-panel BSDs.

Direct excitation of xenon by ballistic electrons emitted from nanocrystalline-silicon planar cathode and vacuum-ultraviolet light emission

— To verify the possible use of energetic electrons for direct excitation of inert gas molecules, a nanocrystalline-silicon (nc-Si) planar ballistic emitter is operated in a high-pressure xenon gas ambience. Under the pulse drive, vacuum-ultraviolet (VUV) light emission is detected without any signs of discharge. The transient behavior of the VUV light emission properly corresponds to that of the nc-Si emitter. In accordance with quantitative analyses of electron-emission characteristics and the VUV output, the electron-to-photon conversion efficiency reaches 81% in the relatively efficient emitter case. The VUV output power is mainly determined from the number of electrons with energies compatible the with internal excitation of xenon. The emission spectrum observed at a pressure of 10 kPa shows peaks at 152 and 172 nm, which are thought to be originated from metastable Xe2* states. In contrast to the case of conventional impact ionization, no near-infrared (NIR) peaks are seen in the spectrum. These results strongly suggest that the incidence of energetic electrons causes direct excitation of xenon molecules followed by radiative relaxation through intermediate states. The generated VUV light can be easily converted to visible light using a phosphor screen. As a discharge-free VUV light emission, this phenomenon is potentially applicable to mercury-free, high-efficacy, and high-stability flat-panel light-emitting device.

39.3: Development of a Low Temperature Process of Ballistic Electron Surface-Emitting Display (BSD) on a Glass Substrate

Ballistic electron Surface-emitting Display (BSD) is successfully fabricated on a glass substrate with low temperature process. 168 (RGB) × 126 pixels, 2.6 inches diagonal full-colour BSD exhibits excellent performance as a flat panel display. Main fabrication process is an anodisation and subsequent electrochemical oxidation process at a low temperature, which will contribute to larger panel size and process-cost reduction.

1/f noise in a-Si1−xCx:H thin films as novel thermistor materials for micro-machined IR sensors

Abstract A superior infrared (IR) sensor of D*=8.0×108 cm Hz1/2/W with a micro-machined structure has been successfully fabricated. An increase in sensitivity was realized by using a boron doped hydrogenated amorphous silicon carbide (a-Si1−xCx:H) film with an activation energy, Ea, and also reducing its noise. Structural uniformity and carrier density were changed by controlling deposition parameters. The 1/f noise (flicker noise) was reduced by decreasing the amount of Si–CH3 and C–Hn bonds in the a-Si1−xCx:H. Though the doping increased the structural disorder, the 1/f noise was also reduced as the doping level increased. We conclude that the 1/f noise does not originate from the structural disorder nor neutral dangling bonds which act as recombination centers, but from the structural non-uniformity causing fluctuations of the carrier conduction. Comparing films with the same Ea at different doping levels and CH4/SiH4 ratio, heavily doped films show lower 1/f noise.

Vacuum-ultraviolet light emission from xenon directly excited by ballistic output electrons of nanocrystalline silicon planar cathode

The effect of electron incidence into xenon gas molecules has been investigated by using a nanocrystalline silicon (nc-Si) planar ballistic emitter. Vacuum-ultraviolet light emission is observed without discharging when the nc-Si device is driven in xenon gas. The emission spectrum of xenon at 10kPa shows peaks at 152 and 172nm which originate from Xe2* radiation. These results strongly suggest that energetic electrons directly excite xenon molecules followed by radiative relaxations. The observed effect is potentially applicable to mercury-free, efficient, and stable flat panel light sources.

14.1: Invited Paper: Fabrication of Ballistic Electron Surface-Emitting Display on Glass Substrate

It is demonstrated that the Ballistic electron Surface-emitting Display (BSD) can be fabricated onto both quartz and TFT Glass substrates and performed excellent characteristics. We also demonstrate the 2.6 inches diagonal 84(RGB)×63 pixels multicolour flat panel display on a quartz glass substrate. BSD promise the possible application to the flat panel display in near future.